Compact document handling system

ABSTRACT

In a copier with a recirculating document handler pivotally mounted to be closable over an imaging station on the upper surface of the copier, and a document inverter, and the capability of automatically copying both sides of documents at the imaging station by utilizing the document inverter to invert documents being recirculated by the document handler, the improvement wherein the document inverter is only partially in the document handler and operatively but non-integrally incorporates a generally planar document chute which is independently integrally mounted to the copier and is not a physical part of or pivotal with the document handler, to provide a more compact document handler with automatic document inversion capability, wherein the document chute is defined by upper and lower baffles for containing and guiding a document for reversal therein by the document inverter, and wherein at least a major portion of these upper and lower baffles are integral to the copier, laterally adjacent to both the imaging station and the document handler, and only operatively connecting with the other portions of the document inverter in the document handler only when the document handler is closed over the imaging station. The document chute has an open end remote from the imaging station, and the document inverter is selectively alternatively operable to provide a document output ejection path through the document chute and out of this open end rather than document reversing therein. The major portion of the upper and lower baffles defining the document chute are preferably on the upper surface of a copy sheet output module (such as a sorter or stapler) mounted to one side of the copier and additionally providing a document receiving tray.

The present invention relates to an improved, more compact, documenthandling system for a copier and more particularly to an improved systemand apparatus for automatically recirculating and inverting or ejectingdocument sheets being copied on a copier platen.

As xerographic and other copiers increase in speed, and become moreautomatic, it is increasingly important to provide higher speed yet morereliable and more automatic handling of the document sheets beingcopied, i.e. the input to the copier. It is desirable to feed,accurately register, and copy document sheets of a variety or mixture ofsizes, types, weights, materials, conditions and susceptibility todamage, yet with minimal document jamming, wear or damage by thedocument transporting and registration apparatus, even if the samedocuments are automatically fed and registered repeatedly, as forrecirculating document precollation copying.

Even with slower copying rate copiers, it has become increasinglydesirable to provide at least semi-automatic document handling (SADH),allowing an operator to "stream feed" originals into an input of thecopier document handler or feeder. The SADH may also comprise anautomatic document handler (ADH) for automatic feeding from a stack ofdocuments, with the document feeder in either case doing the deskewing,feeding and final reistration of the documents into the copyingposition, and then ejecting the documents from the platen automatically.

A preferable document handling system is one that utilizes an existingor generally conventional copier optical imaging system, including theexternal transparent copying window (known as the platen or imagingstation) of the copier. It is also desirable that the document handlingsystem be readily removable, as by pivoting away, to alternatively allowthe copier operator to conventionally manually place documents,including books, on the same copying platen. Thus, a lighter weightdocument handler is desirable. It is also desirable that a documentregistration edge alignment or positioning system be available for suchmanual copying which is compatible with that used for the documenthandler.

In the description herein the term "document" or "sheet" refers to ausually flimsy sheet of paper, plastic, or other such conventionalindividual image substrate, and not to microfilm or electronic imageswhich are generally much easier to manipulate. A highly elongatedocument or copying substrate such as a computer form (CF) pluralsection web, known as fanfold or zig-zag, is referred to herein as a"web" or "CF". The "document" is the sheet (original or previous copy)being copied in the copier onto the "copy sheet", which may beabbreviated as the "copy". Related, e.g. page order, plural sheets ofdocuments or copies are referred to as a "set", or book. A "simplex"document or copy sheet is one having its image and page number on onlyone side or face of the sheet, whereas a "duplex" document or copy sheethas pages and normally images on both sides.

The present invention is particularly suitable for precollation copying,i.e. automatically plurally recirculated document set copying providedby a recirculating document handling system or "RDH". However, thedisclosed system is also compatible with non-precollation orpost-collation copying, such as semi-automatic document handling (SADH)as discussed above. Precollation, collation, recirculative, or RDHcopying, as it is variably called, is a known desirable feature for acopier. It provides a number of important known advantages. In suchprecollation copying any desired number of collated copy sets or booksmay be made by making a corresponding number of recirculations of theset of documents in collated order past the copier imaging station andcopying each document page (normally only once) each time it circulatesover the imaging station. The copies therefrom may automatically exitthe copier processor in proper order for stacking and offsetting asprecollated sets, and thus do not require subsequent collation in asorter or collator. On-line finishing (stapling, stacking and/orglueing, or other binding) and/or removal of completed copy sets maythus be provided while further copy sets are being made in furthercirculations of the same document set.

Some current examples of recirculating document handlers are disclosedin U.S. Pat. Nos. 4,076,408; 4,176,945; 4,278,344; 4,330,197, 4,466,733and 4,428,667. A preferred vacuum corrugating feeder air knife, and atray, for an RDH are disclosed in U.S. Pat. Nos. 4,418,905 and4,462,586. An integral semi-automatic and computer form feeder(SADH/CFF), which may be an integral part of an RDH, as noted in Col. 2,paragraph 2, therein, is disclosed in U.S. Pat. No. 4,462,527.

However, a disadvantage of such precollation copying systems is that thedocuments must all be repeatedly separated and circulated sequentiallyfor copying in a predetermined order a number of times equivalent to thedesired number of copy sets. Thus, increased document handling isnecessitated for a precollation copying system, as compared to apost-collation copying system. Therefore, maximizing document handlingautomation while minimizing document wear or damage is particularlyimportant in precollation copying.

In contrast, in a post-collation copying system, such as with an ADH orSADH, plural copies may be made at one time from each document page andcollated by being placed in separate sorter bins. Thus, the document setneed only be circulated (or manually or semi-automatically fed) to theimaging station once if the number of copy sets being made is less thanthe number of available sorter bins. A disadvantage is that the numberof copy sets which can be made in one document set circulation islimited by the number of available sorter bins. Also, a sorter addsspace and complexity and is not well suited for on-line finishing.However, post-collation copying, or even manual document placement, isdesirable in certain copying situations to minimize document handling,particularly for delicate, valuable, thick or irregular documents, orfor a very large number of copy sets. Thus, it is desirable that adocument handler for a precollation copying system be compatible with,and alternatively usable for, post-collation and manual copying as well.

Although faster, more accurate, and automatic feeding into andregistration of each document at the correct position on the platen tobe copied is highly desired, this is difficult to accomplish withoutskewing (rotating) the document and/or damaging the edge of thedocument, particularly s it is being stopped. One problem is thatdocuments can vary widely in sheet size, weight, thickness, material,condition, humidity, age, etc. Documents may even have curls, wrinkles,tears, "dog-ears", cut-outs, overlays, tape, paste-ups, punched holes,staples, adhesive or slippery areas, or other irregularities. Unlikesets of copy sheets, which generally are all from the same new cleanbatches and therefore of almost exactly the same condition and size,documents often vary considerably even if they are all of the same"standard" size, (e.g. letter size, legal size, A-4, B-4, etc.). Incontrast documents even in the same set may have come from completelydifferent paper batches or have variably changed size with different ageor humidity conditions, etc. Furthermore, the images on documents andtheir fusing can change the sheet feeding characteristics and theseimages may be subject to damage in feeding if not properly handled, e.g.smearing of fresh typewriting ink. Yet it is desirable to automaticallyor semi-automatically rapidly feed, register and copy even a mixture ofsizes, types, and conditions of documents without document jams ordocument damage and with each document correctly and accurately alignedto a desired registration position.

As described in the above-cited patents on recirculating documentfeeders, an important and desirable feature is to provide a built-inautomatic document inverter, automatically actuatable to invert duplexdocuments to provide automatic precollation copying of both sides of aset of duplex documents. However this has heretofore substantiallyincreased the size and weight of the RDH. That is particularlyundesirable for an RDH unit, which needs to be readily pivotal by theoperator up away from the platen for alternative manual (thick, large orvaluable) document copying, and then pivoted back down over the platenfor RDH operation. A major contributor to the increased RDH size due tothe duplex document inverter has been the inverter reversing chute orinversion path and its defining baffles, which must accomodate thedimensions of the largest document to be inverted. As shown in the citedart, various efforts have been made to curve or fold over or otherwisemake more compact the RDH inverting path and its input and outputfeeders, with only limited success. See, e.g., U.S. Pat. Nos. 4,456,236or 7 issued June 26, 1984 to M. H. Buddendeck; 4,330,197 issued May 18,1982 to R. E. Smith et al (its inverter being described in 4,262,895issued Apr. 21, 1981 to S. J. Wenthe); 4,234,180 issued Nov. 18, 1980 toJ. H. Looney; 4,278,344 issued July 14, 1981 to R. B. Sahay; 4,459,013issued July 10, 1984 to T. J. Hamlin et al; 4,176,945 issued Dec. 4,1979 to R. C. Holzhauser et al; and other art cited in these references.Making the inverting path highly arcuate as in said U.S. Pat. No.4,176,945 introduces other problems such as increased sheet feedingresistance and jam tendencies. Furthermore, limiting the effectivelength of the inverter chute or path limits the maximum document sizewhich can be recirculated. Yet making a planar document inverting chuteof appropriate length, even if horizontal, would cause the RDH to bemuch larger than the platen and occupy a large horizontal area,increasing the copier size or depriving the operator of otherwise usefulworkspace on the upper surface of the copier. See, e.g. U.S. Pat. No.4,238,126 issued Dec. 9, 1980 to M. J. Langdon, chute 8 vs platen 2, andFIG. 2; U.S. Pat. No. 4,319,833 issued Mar. 16, 1982 to G. Hidding (noteFIGS. 1 and 2) and U.S. Pat. No. 4,264,067 issued Apr. 28, 1981 to G. M.Adams (not an RDH). Placing the document restacking tray and feeder atone side of the platen rather than over it (inside the RDH) has similarand additional disadvantages, and for that and other reasons theinverter chute generally is located at one side of the RDH, extendingit.

Another desirable feature for an RDH is to provide an alternative SADHmode of operation using the platen transport of the RDH to stream feeddocuments across the platen but then ejecting them from the RDH unitrather then restacking the documents in the RDH restacking tray forrecirculation. The document sheets or web to be SADH copied are alsopreferably seperately inputted. However the apparatus to provide thisalternative SADH operating mode and output also adds to the size,weight, complexity and cost of the RDH unit. Some examples of previousconcepts are disclosed for example in U.S. Pat. No. 4,080,063 issuedMar. 21, 1978 to D. Stemmle; said above-cited U.S. Pat. Nos. 4,176,945;4,192,607 issued Mar. 11, 1980 to C. T. Hage; and U.S. Pat. No.4,391,504 issued July 5, 1983 to T. Acquaviva. Note that said 4,176,945shows part of the recirculating document inverter being utilized forSADH document output ejection (FIG. 8 vs FIG. 9), although both arehighly arcuate and the inverter is a unidirectional loop path notproviding a reversing chute or reversing the direction of documentmovement. The RDH/SADH unit disclosed herein provides the desiredfeatures discussed above and overcomes many of the above-describedproblems and disadvantages. Specifically, it provides a simpler and morecompact RDH taking up a smaller area of the copier upper surface, notsubstantially horizontally larger than the platen, yet also provides adesirably planar and horizontal document inverting chute, and also,utilizing the same apparatus with a different mode of operation, forreduced cost and space, a planar horizontal SADH document output. Thesystem taught herein can handle a wide range of document sizes andweights or stiffness, without deformation, and thereby also reducing jampotentials. The disclosed system utilizes integration for operation withthe copier itself and/or an integral modular attachment for an SADHdocument tray and/or document output module such as a sorter orfinisher.

Some examples of various other patents generally teaching known copierdocument handlers and copiers and control systems therefor, includingdocument and paper path switches and counters, are U.S. Pat. Nos.:4,054,380; 4,062,061; 4,076,408; 4,078,787; 4,099,860; 4,125,325;4,132,401; 4,144,550; 4,158,500; 4,176,945; 4,179,215; 4,229,101;4,278,344; 4,284,270, 4,335,949 and 4,428,666. Conventional simplesoftware instructions in a copier's conventional microprocessor logiccircuitry and software of document handler and copier control functionsand logic, as taught by the above and other patents and variouscommercial copiers, are well known and preferred. However, it will beappreciated that the functins and controls described herein may bealternatively conventionally incorporated into a copier utilizing anyother suitable or known simple software or hard wired logic systems,switch controllers, etc. Suitable software for functions illustrated ordescribed herein may vary depending on the particular microprocessor ormicrocomputer system utilized, of course, but will be already availableto or readily programmable by those skilled in the art withoutexperimentation from the descriptions and references provided herein.

As shown in the above-cited art, the control of exemplary document andcopy sheet handling systems in copiers may be accomplished byconventionally actuating them by signals from the copier controllerdirectly or indirectly in response to simple programmed commands andfrom selected actuation or non-actuation of conventional copier switchinputs by the copier operator, such as switches selecting the number ofcopies to be made in that run, selecting simplex or duplex copying,selecting whether the documents are simplex or duplex, selecting a coopysheet supply tray, etc. The resultant controller signals mayconventionally actuate various conventional electrical solenoid or camcontrolled sheet deflector fingers, motors or clutches in the copier inthe selected steps or sequences as programmed. Conventional sheet pathsensors, switches and bail bars, connected to the controller, may beutilized for sensing and timing the positions of documents and copysheets, as is well known in the art, and taught in the above and otherpatents and products. Copying systems utilize such conventionalmicroprocessor control circuitry with such connecting switches andsensors for counting and comparing the numbers of document and copysheets as they are fed and circulated, keeping track of their generalpositions, counting the number of completed document set circulationsand completed copies, etc. and thereby controlling the operation of thedocument and copy sheet feeders and inverters, etc.

It is a general feature of the system disclosed herein to overcomevarious of the disadvantages and limitations discussed above and in thecited references.

A specific feature disclosed herein is to provide in a copier with arecirculating document handler pivotally mounted to be closable over animaging station on the upper surface of the copier, and a documentinverter, and the capability of automatically copying both sides ofdocuments at said imaging station by utilizing the document inverter toinvert documents being recirculated by the document handler, theimprovement wherein:

said document inverter is only partially in said document handler andoperatively but non-integrally incorporates a generally planar documentchute which is independently integrally mounted to said copier and isnot a physical part of or pivotal with said document handler, to providea more compact document handler with automatic document inversioncapability,

wherein said document chute is defined by upper and lower baffles forcontaining and guiding a document for reversal therein by said documentinverter,

and wherein at least a major portion of said upper and lower baffles areintegral to said copier, laterally adjacent to both said imaging stationand said document handler, and only operatively connecting with theother portions of said document inverter in said document handler onlywhen said document handler is closed over said imaging station.

Further features which may be provided by the method and apparatusdisclosed herein include those in which:

said document chute has an open end remote from said imaging station,and said document inverter is selectively alternatively operable toprovide a document output ejection path through said document chute andout of said open end rather than document reversing therein;

said at least major portion of said upper and lower baffles definingsaid document chute are integral to copy sheet output receiving meansintegrally mounted to one side of said copier, and said copy sheetoutput receiving means also has an integral document catch traycommunicating with said document chute;

said document chute has an open end in said copy sheet output receivingmeans, and said document inverter is adapted to alternatively provide adocument output ejection path through said document chute and out ofsaid open end, and wherein said copy sheet output receiving meansfurther includes a document receiving tray operably connecting with saidopen end to collect documents ejected therefrom;

said at least a major portion of said upper and lower baffles definingsaid document chute are integral to document collection tray meansintegrally mounted to said copier, and wherein said document chute opensinto said document collection tray means, and wherein said documentinverter is adapted to alternatively provide a document output ejectionpath through said document to chute and into said document collectiontray means, which is adapted to collect documents so ejected;

sid document chute is generally parallel to and contiguous with saidupper surface of said copier;

said document inverter includes a selectably reversible document feedingmeans integral said document handler and in direct document feedingcommunication with said document chute when said document handler isclosed over said imaging station to provide reversible document feedingto and out of document chute of said document inverting; and whereinsaid document inverter further includes upper and lower minor baffleportions smaller than the dimensions of documents to be reversed thereinwhich baffle portions are automatically aligned with said upper andlower baffles integral said copier when said document handler is closedover said imgaing station; and

said reversible document feeding means is integral said upper and lowerminor baffle portions.

All references cited herein, and their references, are incorporated byreference herein for appropriate teachings of additional or alternativedetails, features, and/or technical background.

Various of the above-mentioned and further features and advantages willbe apparent from, but are not limited to, the following specific exampleof one application of the invention. The following description of thisexemplary embodiment includes drawing figures (approximately to scale)wherein:

FIG. 1 is a partly schematic cross-sectional front view of an exemplaryrecirculating document handler and copier incorporating one example ofthe present invention;

FIG. 2 is a perspective exterior view of the copier and RDH of FIG. 1;and

FIG. 3 is an enlarged rear cross-sectional view of the RDH of FIG. 1.

Referring to the one example of FIGS. 1-3, and in particular FIG. 1, itwill be appreciated that the system described herein may be utilizedwith various document handlers and copiers, such as those incorporatedby reference herein. By way of background, the exemplary RDH details ofFIG. 3 will be discussed first. Thus while the connecting portion of anexemplary copier 10 here includes the illustrated copier platen 12 and asimple full-frame optics system 14, it will be appreciated that thedisclosed registration system may be utilized, for example, with ascanning optics system, as previously noted. The optics system 14 is oneexample of an optics system providing variable magnification of thedocument image on the platen 12 onto a selected copy sheet. Thisincludes at least two or more selectable choices of reduction, so as tobe able to copy for example, legal size documents onto letter size copysheets, and the like, as is well known per se. Preferably, but notnecessarily, this choice of reductions is continuous over a substantialrange so as to provide a wide variety of reduction selections.Additionally, but not necessarily, one or more choices of document imageenlargement may be provided by the optic system 14. The mechanisms forproviding such optical reduction or magnification changes, by lens,mirror and/or platen repositioning, are well known in the art, and aredisclosed in references cited above, and need not be described herein.The operator selection of the desired reduction or magnification of thedocument image is conventionally made on the operator console (keyboard)of the copier controller 16. Illustrated here are selectablemagnification/-reduction switches or buttons 17 on the operator consolewhich connect with and control the conventional programmable copiercontroller 16 as previously described above. Actuation of a selectedmagnification or reduction switch 17 accomplishes that change and alsoprovides a control signal in the controller 16 indicative of thatselected magnification or reduction ratio. Alternatively oradditionally, a lens or mirror position encoder 15 may be providedconnecting with or directly sensing the movement of the optical elementsof the optical system 14 to provide signals indicative of the actualrepositioning of the optical elements and therefore of the actualpresent reduction or magnification ratio of the optical system 14.

Also connecting with the controller 16 are copy tray selector switches18. Where different size copy sheets are placed in different copy traysor cassettes, as is conventional, the selection of a particular switch18 provides a signal to the controller indicative of the size of thecopy sheet onto which the document image is being copied. Alternativelyor additionally, as shown in the lower right-hand side of FIG. 1, actualsheet size sensors may be placed in the individual copy sheet trays orin the paths of the copy sheets being fed from these copy sheet trays todirectly measure the actual copy sheet size, which sensors are connectedto the controller 16, as shown, to provide signals directly indicativeof the copy sheet size being utilized for that particular copy (note theabove-cited art references in this regard).

Thus, it may be seen that the controller 16 is provided with signalsindicative of both the size of the copy sheet being utilized and alsothe ratio of the optical reduction or magnification of the documentimage onto that copy sheet. As will be fully further described herein,both of these signals are utilized for document registration. Thisinputted electrical signal information as to the copy paper size and theselected magnification or reduction ratio is combined with otherinformation to calculate the proper document imaging position on theplaten as a function of both said inputs. This is combined withinformation as to the sensed timing/position of the trail edge of thespecific document sheet being copied as it is fed onto the imagingplaten 12. A calculated variable stopping position of the document isprovided which eliminates any need for the document to hit a mechanicalregistration stop, i.e. it completely avoids "hard stop" driving of thedocument sheet into a mechanical registration edge or gate.

First, however, the exemplary RDH/SADH system 20 disclosed here will bedescribed in further detail. It includes an alternate SADH input 21 intowhich individual document sheets or computer form (fanfold) web may befed for copying. This SADH mode utilizes the same platen documenttransport 22 and its drive (comprising a servo motor 24 with encoder)and other components shared with the RDH mode of operation of thisdocument handler 20. For the RDH mode, i.e. for recirculating(precollation) document copying, the set of original documents 27 arestacked face-up into the document tray 26. They are sequentially fed outfrom the bottom of the stack by a vacuum corrugating feeder 28, asdescribed in above-cited references.

The RDH/SADH unit 20 may be alternately utilized as a non-recirculatingautomaic document feeder (ADF) by placing the documents in tray 26 butnot returning them to tray 26 after copying. Preferably such an ADFwould utilize a top feeder, i.e. the bottom feeder 28 would be removedor inactivated for ADF operation, and an ADF top feeder could beinserted instead. The ADF top sheet document feeder could be, forexample, a simple "flapper" feeder utilizing plural sheet feedingflappers of the type disclosed in U.S. patent application Ser. No.627,269 filed July 2, 1984 by G. M. Garavuso, et al (D)/84049), commonlymounted and rotatably driven on a single shaft adjacent the top frontedge of tray 26.

Additionally connected to the controller 16 are document sheet leadand/or trail edge sensors 30, 32, 33, and 34 strategically positionedaround the RDH document recirculation path of the RDH/SADH 20, as willbe further described herein. Additional sensors disclosed here are anSADH/CFF input sensor 36 for documents being inputted into the SADHinput 21, and a document exit sensor 38, both also connected to thecontroller 16. Also provided (optionally) are three document widthsensors 31 spaced transversely of the document path to measure the widthof the document and thereby control the magnification ratioautomatically, as will be described. All of the document path sensorsdescribed here are preferably of a commercial photooptical type whereinthe entrance or exit of a document sheet through a conventionalphoto-diode optical path across the document path provides an outputsignal directly indicative of the passage of the lead edge and/or trailedge of the document past that fixed position at that time, relative toa clock count time in the controller 16, and relative to an encodercount of the transport servo 24 movement encoder.

A document set separator and stack height sensor 40 is connected to thecontroller 16 to provide conventional signals, i.e. a signal indicativeof no documents being present in tray 26, and a signal upon eachcirculation of the document set (both by dropping of the set separatorfinger through an aperture in the bottom of the tray 26). The sensor 40may also provide signals indicative of the approximate height orthickness of the stack of documents 27 in the tray 26, at the time thefinger is automatically reset on the top of the stack, which informationis utilized to control the air-knife pressure of the VCF feeder 28, asdescribed in U.S. Ser. No. 373,919 filed May 3, 1982 (D/82035) and artcited therein.

Also in the same document recirculation path to and from the RDH tray 26are plural spaced document sheet feeding roller pairs. Here, theseroller pairs preferably include a neoprene rubber or other relativelyhigh friction driven roller and a mating idler roller of smoothstainless steel or the like.

The first specific roller drive provided for the documents in the RDHpath here are a take-away roller driver 42 and its mating idler 44. Theyare slightly downstream of the document exit from the tray, forproviding take-away feeding of a document after it has been separatedfrom the stack and initially fed out by the vacuum corrugating feeder28.

The first sensor 30 detects the lead edge of this document being fedinto the nip of these take-away rollers 42 and 44 by the VCF feeder 28.The sensor 30 provides a jam condition check signal if the document isnot sensed within a prescribed time window. The take-away rolls 42 and44 are aligned with, i.e. at a zero degree angle to, the document path,so as to feed the document sheet on through arcuate document guides orbaffles 70 of the recirculation path to the next pair of drive rollers46 and 48 without inducing skew or transverse movement of the document.The deskewing roller driver 48 and its mating deskewing roller idler 46are illustrated in enlarged detail in FIGS. 2 and 3. They form part ofan automatic document side edge registration and deskewing system, aswill be further described herein, in which the takeaway idler 44 issolenoid retracted away from the take-away driver 42 after the lead edgeof a document has entered the nip between the deskewing rollers 46 and48. That opens the nip between rollers 42 and 44 and thereby releasesthe document sheet for deskewing and lateral registration control onlyby the rollers 46 and 48. The vacuum force has been previously removedfrom the VCF 28, to release the trail edge of the document therefrom.That is done as soon as the document lead edge area is acquired by thetake-away rollers 42 and 44.

The acquired document may be temporarily stopped at a "wait" stationposition before it is transported onto the platen, i.e. to briefly waitfor the completion of copying of the preceding document already on theplaten. Except for the first feed of the first document, the preferablewait station stopping position 88 of a lead edge of the document isslightly beyond the nip of the deskewing rollers 46 and 48. This may becalculated by a timing count initiated by the lead edge of the documentpassing the first sensor 30. The distance and velocity of the documentmovement is known, because the respective document driving rollers 42,48 in the document path are directly driven by servo motor 24, theencoder of which provides the timing count pulses, and the document isalways under positive control in at least one document feeder nip.

Once feeding of the document sheet in the wait station 88 is initiated,the lead edge of the document passes the second, registration, sensor 32slightly upstream of the upstream entrance to the platen transport 22.The sensor 32 is also multi-functional. It looks for the arrival of thelead edge of the document at the appropriate time, as a jam check. Thenit looks for the arrival of the trail edge of that document within anappropriate time window (count) for the largest document to be fed fromtray 26 to provide a second jam check at that sensor 32 position. Mostimportantly, the sensing of the trail edge of the document by sensor 32as it is being fed onto the platen 12 by the platen transport belt 50 ofthe platen transport 22 initiates a process of calculated timedregistration movement to stopping position of the document, as will befurther described herein.

On the first feed of the first document to be recirculated there isoptionally provided an alternative initial wait station at a set ofdocument width detector switches 31 upstream of the platen 12. The firstdocument fed is held here briefly for calculation of which one of astandard set of document widths in a look-up table in non-volatilememory in controller 16 corresponds to the occlusion of one, two, or allthree of these sensors 31. The positions of sensors 31 are spacedtransversely across the document path so that, for example, documents ofstandard U.S. letter size will occlude only one sensor 31, documents ofthirteen inch length will occulude two sensors 31 but not the thirdsensor 31 and documents of fourteen inches or greater length willocclude all three sensors 31. The three sensors 31 are connected tocontroller 16 to provide the document size from the look-up table,and/or to directly control the optics system 14 to provide a suitableimage reduction of that size document to fit onto the selected size ofcopy sheet available (automatic "force-fitting").

The platen transport belt 50 is preferably a single wide white uniformlylight reflective belt of a conventional high friction material. The belt50 provides, together with the illustrated backing pressure rollers forincreasing the normal forces, feeding of each document without slippageonto and across the platen 12 into registration. After copying the beltdrive motor 24 restarts to eject that document while feeding on the nextdocument. The belt 50 is driven through one of its two end rollers by adirect driving connection (schematically illustrated by connecting line52), through an automatically electrical engaged clutch, to the servomotor 24. The servo motor 24 has a rotational encoder, preferably aconventional integral shaft encoder. This encoder provides encoder countsignals (pulses) to the controller 16 cumulatively directly indicativeof the amount of rotation of the servo motor 24 and therefore thecorresponding movement thereby of the transport belt 50. The transportbelt 50 is slowed down and temporarily stopped for the imaging of thedocument at a desired belt movement distance along the platen when apredetermined desired count of such servo encoder 24 output pulses tothe controller 16 has been reached, by count comparison, as will befurther described. Immediately following copying the servo motor 24 isrestarted the same direction to transport documents unidirectionallywith belt 50 for ejection from the opposite end of the platen from whichthe documents enter, and for simultaneously feeding in the nextdocument.

The exiting document passes a third jam sensor 33 adjacent thedownstream platen edge. This sensor 33 also forms part of a system forinverting duplex documents here, as will be described.

Documents which are not being either inverted, or ejected from thedocument handler, e.g. simplex documents being recirculated back to thetray 26, are fed on directly to return transport roller paris 54 viabaffles 78. Rollers 54 in turn feed the document on to restack rollerpairs 56, which provide document corrugation and ejection of thedocument back on top of the stack of documents in the tray 26.

Alternatively, for either document ejection or document inversion,documents fed off platen 12 by belt 50 are diverted by a solenoidactuated diverter gate 58 (in its dashed-line position) into a first setof exit roller pairs 59. Then the document is fed through a one-waygravity inverter gate 60. The gravity inverter gate 60 is deflectedupwardly into its illustrated dashed-line position by the lead edge of adocument fed therein by the rollers 59. After the trail edge of thedocument passes the gate 60, the gate 60 drops by gravity forcedownwardly into its solid-line position.

For document inversion the document sheet movement direction is thenreversed after the document is well past the gate 60 and gate 60 hasdropped. Reversing a (recirculating duplex) document for such inversionis accomplished by reversing the direction of rotation of independentlyand reversibly driven exit rollers 62 downstream of the gate 60 . Therevers-driven document is deflected upwardly by gate 60 into a different(reversed document) path extending into the rollers 54 for restacking intray 26 with inversion. The sheet guides or baffling illustratedprovides a generally "Y" shaped inverter path for the documents beinginverted with a generally horizontal portion forming the base of the"Y". Note however, that only a portion of a normal inverting chute isprovided by this portion 61. For normal size documents, at the time theyare reversed by reversal of rollers 62 only a portion of the document isin this horizontal partial chute 61, while the rest of the document(approximately half) is extending out beyond both rollers 62 and the endof the chute 61. Both rollers 61 and exit sensor 38 are adjacent theopen end of partial chute 61.

The timing of the reversal of roller pairs 62 for each sheet beinginverted is preferably a count in controller 16 initiated from thesensing of the trail edge of that document at sensor 33. That is, acount in servo encoder pulses providing sufficient travel for the trailedge of the document to be transported from sensor 33 past inverter gate60. That time count is also sufficient for the document to have beenfully, centrally, acquired by rollers 62 before the rotation of rollers62 is reversed. The rollers 62 are located closer to gate 60 than themovement dimension of the smallest document to be inverted, preferablyless than approximately half the dimension of a normal (e.g. 81/2" wide)document.

Alternatively, but less desirably the lead edge of a document may besensed at exit sensor 38 to initate after a count the reversal ofrollers 62. In either case, the inverter timing count is from the servomotor 24 encoder, since the document movement corresponds thereto,because of the non-slip drive of the document by belt 50 and rollers 59,which are both driven by servo motor 24.

Rollers 62 are preferably driven by a separate small reversible ACmotor. However, for insuring uniform speed drive, especially for CFFweb, the rollers 62 are preferably clutched into the servo motor 24drive system for SADH input 21.

The inverter system described above alternatively provides for documentejection of documents not being circulated (not being returned to tray26). For such non-recirculating document feeding and copying with theRDH/SADH 20, documents may be inserted at the SADH input 21 and fed inthrough the nip formed by an SADH roller driver 64 and mating idler 66.The idler 66 may be solenoid cammed down away from the driver 64 fordocument insertion. During insertion and initial registration anadjacent SADH gate 68 is solenoid actuated into the document path forthe SADH entrance 21 (only). When the controller 16 initiates SADHfeeding, by sensing SADH input at sensor 36, the SADH input gate 68 ismoved out of the SADH document path and simultaneously idler 66 islifted into driving engagement with the driver roller 64 to feed thedocument towards the same platen transport 22 for coying. The SADHdocument input path merges into the RDH input path via integralbaffling. As the document is fed off the platen the gate 58 is raisedautomatically in response to said SADH input. SADH documents are fed outby rollers 59 and 62 and ejected rather than being inverted. The rollers62 are not reversed for SADH input. For SADH the rollers 68 provide fordocument ejection, rather than inversion. Likewise, the horizontalportion 61 of the "Y" path of the inverter baffles in which rollers 62are located provides an initial partial output path or chute fordocuments in this mode, rather than an inverter chute, i.e. all thosesheets or web fed into the SADH input 21 are fed completely out pastexit sensor 38 using the inverter system.

In the recirculating document copyng (RDH) mode of operation of thedocument handler 20 all documents 27 fed from the stack 26 are initiallyinverted once, and deskewed, in hemi-cylindrical first inversion baffles70. These baffles 70 here include at one ide or edge a correspondinglarge radius curved edge registration guide 72, illustrated in enlargedcross-section in FIG. 2. The guide 72 is preferably a single clearplastic molding containing an integral arcuate (hemi-cylindrical) slot74 and a linear SADH input slot intersecting into a common base slotleading to the platen. The arcuate slot 74 has smooth generally parallelsides closely spaced from one another, (preferably substantially lessthan one centimeter) but spaced apart by a distance substantiallygreater than the thickest document to be fed. A suitable such slot widthis approximately 2.5 mm, measured perpendicular to the document plane.The slot 74 depth to its bottom 76 is preferably greater. Approximately15 mm has been found suitable. The bottom 76 of the slot 74 provides asmooth, low friction, surface against which one edge of each documentsheet is deskewed and side-registered and slides along as it is beingfed by deskewing rollers 48 and 46 through the arcuate baffles 70. Thatis, as the document is being fed away from the stack bottom feeder 28 tothe nip between the platen 12 and the platen transport belt 50. Thestrict document control provided by the continuous confinement of theedge of the document being deskewed and side registered inside the slot74 enables this to be done even though the document is being highlydeformed while this is bein done.

With this system, each document sheet is accurately side-registered onlyjust before it is fed onto the platen 12, and each time it iscirculated. The document cannot skew or deregister before beingimmediately acquired by the non-slip platen transport. No on-platen sideregistration, or downstream side registration, or accurate restackregistration is required, which is highly advantageous, as previouslydescribed. Likewise, all deskewing is accomplished in this same step,and lead edge deskewing is not required anywhere in this system. Theother transport rollers 42, 44; 54, 56, 59 and 62 need only provide forlinear, non-skewing, feeding so as not to induce uncorrectably grossside misregistration or skewing in the recirculation process. Since theplaten transport 22 does not allow slippage of the document relativethereto, the upstream side registration and deskewing provided in thissystem is strictly maintained as the document is transported across theplaten by the belt 50 into the desired registration position. As noted,such a non-slip platen transport system is practical only with upstreamdeskewing of the document. Conventional on-platen deskewing against amechanical registration edge is not practicable with a non-slip platentransport.

A conventional second set of inversion baffles 78 between the platen 12and restack rollers 56 provides the second turn-over of a document beingreturned to tray 26. The baffles 78 are integral to and form the ends ofthe two upper branches of the "Y" inverter path descirbed above inoperational communication with the partial baffles 61. The baffles 78,61 and all other baffles in the DH 20 other than 70 do not have edgeguides and therefore do not have any document edge drag. Likewise, therestacking side guides (not illustrated here) in the tray 26 can besufficiently widely spaced so as not to have any frictional or otherresistance to restacking, because in this system these side guides arenot providing the fine or final edge registration and deskewing for thedocuments, merely gross positional restacking.

Discussing further this upstream side registration and deskewing systemdisclosed herein, as shown particularly in FIGS. 2 and 3, and as furtherdiscussed in the above-cited U.S. Pat. No. 4,179,117, an appropriatelimited sideways or lateral vector force component is induced in thedocument sheet by the different friction and oppositely skewed rollers46 and 48. Here, the high friction driving roller 48 is preferably at anangle of approximately 31/2 degrees toward the document side edgeregistration wall (the slot 74 bottom 76 in the edge guide 72). Theopposing smooth low friction idler roller 46 is here skewed in theopposite direction, away from the edge guide 72, by approximately 7°.The lateral vector force component of wheel 48 continuously urges theedge of the document fully into the slot 74 until it is fully abuttingthe slot bottom 76, which edge registers and deskews that documentsheet. The opposing skew roller 46 then assists the resistance of theslot bottom 76 to further attempted lateral document movement force byrollers 48. The slot bottom 76 is parallel the primary direction ofdocument motion.

Most importantly, because slot 74 and the rest of baffles 70 arecontinuously arcuate, the document is likewise arcuately curved therein.This provides high beam strength. That is, deskewing and sideregistration is driven by rollers 46 and 48 at an intermediate area inwhich the document sheet beam strength has been maximized by thedocument being highly curved into a closely controlled semi-cylindricalconfiguration, which very greatly increases the resistance of thedocument sheet to wrinkling or buckling (and therefore jamming) duringthis edge registration and deskewing process. The close spacing of theopposite sides of the slot 74 prevents even flimsy sheets fromwrinkling, waving or buckling from the forces deskewing them.

With this system, deskewing and side registration are provided with amaximum stiffness or strength of the document sheet, and can be providedfor documents too thin and flimsy for deskewing and side registration ina normal planar configuration. This type of document is easily damagedby conventional lead edge registration deskewing. Thus, the presentsystem increases the latitude and reliability of document feeding in a"soft-stop" or non-mechanical and non-deskewing platen transportregistration system, and enables the latter to be utilized effectivelyby feeding pre-deskewed documents directly thereto even if they are verylightweight, filmsy sheets.

As noted above, the take-away roller idler 44 is raised automatically bya solenoid or cam as soon as the document is under the control of thedeskewing rollers 46 and 48. This releases the trailing area of thedocument from rollers 46 and 48 and therefore from any lateralresistance or impediment by any transports to side registration anddeskewing by the rollers 46 and 48. Thus, as soon as, and as long as,the document sheet feeds through the rollers 46 and 48, theycontinuously maintain a constant urging of the document edge against theslot bottom 76. The document edge slides freely in slot 74 because theedge guide 72 (preferably a monolithic molding) provides a continuousslot 74 with smooth surfaces all extending continuously from the outletof the stack feeder 28 to the inlet of the platen transport 22. Also,the slot 74 and the rest of the baffles 70 have a large radius (greaterthan approximately 5 cm.) and are not skewed. The two inputs to the slot74 preferably have smoothly flared (wider) openings to guide documentstherein.

Additional time is provided for this separating of the nip between theinitial or take-away rollers 42 and 44 by a normal pause in the feedingof the document sheet just after the lead edge thereof has passedthrough the rollers 46 and 48. Reference numeral 88 is indicative ofthis normal wait station of the leading edge of the document. This pausemay be very brief, or entirely eliminated, e.g. for the first documentand for an initial non-copying (counting) "slew cycle" circulation ofthe documents. However, this pause may be substantial in the case of asecond and subsequent documents being copied. These subsequent documentsare stopped when their lead edge reaches the wait station 88 while theprevious document is being copied on the platen 12, by stopping rollers48.

Another, separate, and different deskewing and side registration systemis provided for the SADH input 21. As particularly shown in the bottomview of FIG. 4, the idler roller 66 for this input is also skewed at 7°away from the side edge guide. However, here the high friction drivingroller 64 is angled at approximately 7° toward the side edge guide. Theside edge guide is an integral extension of the guide 72, providing aseparate but intersecting branch of the same size and shape as slot 76and having a bottom coplanar with slot bottom 76. The wait station fordocuments being presented to this SADH input 21 is at the SADH gate 68.Documents from the two wait stations 68 and 88 are fed on equivalentlyshort paths into a common position at the entrance to the transport 22.However, since these two wait stations are separate and non-interferingwith one another, documents may be fed to be copied from either waitstation or alternately upon command without time delay (copier pitchloss). The presence of a document at the SADH mode sensor 36 provides asignal which may be utilized to automatically rapidly interrupt thefeeding of documents from the RDH tray 26 even if feeding therefrom isin process, i.e. even if a document is already at wait station 88 in theRDH mode. Thus, copying interruption time for changing between copyingmodes is eliminted or minimized. Since the duplex document inversionsystem 58, 59, 60, 62 is at the opposite side of the platen from theSADH input 21 they do not interfere with each other either. In fact, asnoted, they cooperate, by sharing the same output/inverter path and gate58 and drives 59 and 62 and sensor 38.

Deskewing by the SADH input rollers 64, 66 occurs continuously, both asthe document is inserted into the gate 68 and also after the gate 68 isopened and the document is being fed to the bottom transport 22.

It will be noted that, unconventionally, the document input (preplatenor feed and deskewing) rollers 46, 48 and 64, 66, are single rollerpairs acting along one edge of the document sheets, rather than aplurality of rollers extending across the document sheet. That is, thetransporting, deskewing and side registering of the document sheets fromtheir input to the platen is done by gripping the documents onlyadjacent one side edge thereof by small frictional rollers, rather thanby conventionally utilizing plural or elongated rollers extendingtransversely across the sheet transversely to its feeding direction.

The following discussion relates to further details of the registrationof the document sheets for copying on their other or diagonal axis, i.e.registration of the lead edge of the document in its direction ofmovement. This is accomplished here on the platen by the controlledstopping position of servo-motor drive 24, as controlled by thecontroller 16 utilizing the integral encoder pulse output of the servomotor 24. A variable registration control system is provided utilizingthe control of servo-motor 24 for controlling the document to stop at adesired calculated stopping position. An example of such a calculatedactual registration position of the lead edge of a document isillustrated at 92. This actual document stopping position 92 iscalculated relative to a preselected ideal registration position for thelead edge of the document. Here this desired or ideal position isclosely adjacent the downstream edge of the platen, and is illustratedat 90. However it could be elsewhere on the platen. Note that the platen12 here is much larger than the normal actual or active image areathereof. The latter is the actual document size divided by themagnification ratio, i.e. the actual image area "seen" by the copieroptics 14 is increased by the degree of optical reduction. The documentis desirably placed accurately within this active image area of theplaten with the downstream edge of the document at "registration", i.e.at the downstream edge of the active image area, wherever that may be onthe platen.

Note that with this system the downstream or leading edge of thedocument is preferably registered automatically at a variable position92 normally but not necessarily adjacent the downstream edge of theplaten. However, in this system the calculation for registration isbased upon and initiated by the sensing of the passage of the trail edgeof the document at sensor 32 before the trail edge of the document wasfed onto the upstream edge of the platen. The latter is desirablebecause it occurs after the rest of that document has been securelyacquired and is in non-slip transporting engagement with the platentransport 22, i.e. after almost all of the document is held between thelower flight of the belt 50 and the platen 12. This lower flight of belt50 is pressed against the document by plural backing rollers to preventany document slip or skewing.

Registration here is the position and time at which the document isstopped. Alternatively, it could be the point in time at which theillumination optics are flashed, if full frame rapid flash illuminationis available in the copier. In the latter case the document transportwould not need to actually stop, i.e., the document would be onlyoptically "stopped" by taking its image rapidly at the calculatedregistration position.

The document is registered at its proper desired imaging position on theplaten by detecting the trail edge of the document and then counting(clocking) electrical pulses generated by the document feeder 22, whichis feeding the document across the platen, until they reach apre-calculated desired count from that point in time, to initially ameasured stop. The servo drive 24 encoder provides an accurate pulsecount corresponding directly to the movement of the transport 22. Theplaten transport 22 here is driven unidirectionally at all times, sothere are no backlash or tensioning errors between the drive 24 and theactual movement of the belt 50. The copier controller 16 begins a countof the encoder output of the servo motor 24 towards registration uponthe actuation of the sensor 32 by the trail edge of the document. Fromthe relative timing of the document in the cycle and the clearance ofthe document past the sensor 30 or 36 at that point in time, and/or theprior lead edge signal from that document at sensor 32, the controller16 knows that it is the document trail edge it is sensing at 32 at thattime and not the lead edge. The sensing of the document trail edgeinitiates the count-down to the measured registration stopping positionof the document transport. As noted above, the encoder pulse count towhich that count-down must reach is based on a prior computation in thecontroller 16 combining input information as to both the copy paper sizeand the selected magnification or reduction ratio at which the documentimage is to be magnified or reduced in copying onto that copy sheet.

That is, this system stops the document drive 22 in response to thecalculation of where the document should ideally be stopped on theplaten as a function of both the selected or measured copy size and aselected or measured magnification/reduction ratio. The magnificationratio is, of course, a function of the position of the mirrors andlenses and conjugates between the platen 12 and the photoreceptor of thecopier, as is well known in the art. However, as indicated above, theselected reduction or magnification ratio utilized as an input to thecontroller 16 for the present system may be from either or both of twoinputs, the switch selection (the ratio selector switch 17 or dial anddisplay on the copier console) and/or the lens or mirror positionencoder 15 sensing the resulting actual position of the opticalcomponents. Thus, for example, if the operator selects a "normal" or 1to 1.01 (slight overfill) copying rato with that switch 17, thatinformation is inputted to the controller 16 for the registrationcalculation here, and also to normally cause the optics 14 to assume thecorrect position for that magnification ratio, and the optics encoder 15will then provide a confirmatory signal thereof to the controller 16 ofthat same magnification ratio.

The other preliminary input to the registration position computation forthe encoder count-down value is a signal corresponding to the copy papersize. That information may also be inputted diretly from the consolecopy tray selector at a selected switch 18, and/or from copy sheet sizesensors. Here these may be sensors in the paper path or in the copysheet trays conventionally providing indications of the paper size.Those signals may be restricted or converted to a limited number or"standard" paper sizes for a particular copier and country of use. Thebuttons 18 may be preset to select one of those local standard sizes.That is, to provide a paper size of "PS" signal which is a selected oneof a limited number of sets of precalculated signals respectivelycorresponding to a preselected limited number of paper sizes which havebeen stored in the non-volatile memory of the copier. These areconverted by the controller 16 to their corresponding dimensions, in theregistration movement direction, in servo 24 encoder counts equivalentsof those dimensions, i.e. as if the copy sheets were beng transported bythe platen transport drive 22 by that same distance.

As indicated, alternatively or additionally to simply inputting thepaper size selection from switches 18, copy size sensors may be providedas schematically illustrated in the lower right-hand side of FIG. 1,associated with the paper trays shown there, or located elsewhere in thepaper path. Actuation of a particular sensor or sensors along a spacedline of plural sensors indicates paper of that approximate dimension.The connecting controller 16 then preferably retrieves from a table orstore in its non-volatile memory a signal, in corresponding encodercounts, corresponding to the closest copy sheet size which would actuatethat copy sheet sensor and would fit in the particular tray in whichthat sensor is located and/or from which copy tray feeding has beenselected. This converts the sensing of an approximate copy sheet sizewith the sensors to a standardized or exact copy size output signal inencoder counts.

Alternatively, particularly if the copier is of the type utilizingseparate dedicated copy paper trays or removable cassettes for specificsizes of copy sheets, the controller 16 will automatically assume thatthe insertion of a particular tray in the copier, or the selection ofone selector switch 18 for a particular tray, implies the feedingtherefrom of only one particular standard size copy sheet, andautomatically provides an encoder count signal corresponding thereto forthe registration calculation from a conventional table, conventionallyprogrammed in its non-volatile memory.

As indicated, the document drive 22 is stopped to stop the document atthe desired registration position in response to a calculation combiningthese input signals, in encoder counts, corresponding to both the copysize and the magnification or reduction ratio. This combined calculationprovides a servo encoder count which tells the servo drive 24 preciselyhow far it is to be driven from the time the document trail edge isdetected by the sensor 32. This calculation provides information inadvance of said stopping of where the document transport is to bestopped. Therefore it is utilized to provide a preprogrammed controlleddeceleration (slowdown) stop of the servo 24 rather than a hard stop. Ahard stop could cause slippage of the document relative to the belt. Asnoted, the document is registered solely by the controlled stoppage ofthe transport 22 in the desired registration position. The document isnot stopped by any registration gates, fingers or other mechanicalstops, and does not stop relative to belt 50.

Although the stopping position varies in accordance with the copy papersize and image reduction/magnification, other positional criteria may beadded thereto. That particularly includes the desirable optionaladdition of a programmable margin shift. That is, an additional inputfor shifting of the stopping position of the document on the platen byan additional preselected distance from the calculated stopping positionso as to correspondingly shift the position of the document image on thecopy sheet to provide a corresponding change in the edge margin of thecopy sheet. That is particularly useful for assuring an adequate leftside margin for binding of the second side of a duplexed copy sheet.This additional registration shift for a margin change or otherwise canbe provided simply by another illustrated switch or knob selection onthe console input to the controller 16 to add or subtract a selectedmargin shift. This switch actuation tells the controller 16 to add anumber of servo encoder counts to the count-down calculationcorresponding to the selected additional movement of the platentransport 22 before it stops for copying, e.g., to add up to plus orminus 13 millimeters of further transport 22 movement.

The specific calculation for registration stoppage of the transport 22here may desirably be done by an equation which corresponds to theexpression "REG=DIST-(PS/MAG)+SHIFT". In this expression of thecountdown calculation, REG is the calculated total number of servo 24encoder counts by which the document transport 22 is to be driven aftertrail edge sensing. That is, the transport 22 will be stopped bycontroller 16 when the number of encoder pulses from the servo 24accumulated after the actuation of sensor 32 reaches this calculatedcount. The DIST in this equation is a constant. It is a preset number ofservo encoder counts, corresponding to a desired distance in servoencoder counts between sensing means 32 and a preselected idealregistration position 90 where the lead edge of the document would beadjacent the downstream edge of a platen, calculated for a documenthaving a conventional or known dimension in its feeding direction. PS isthe selected paper size in servo encoder counts as discussed above. SaidPS is divided by MAG, which is the selected magnification or reductionratio. SHIFT is the optional portin of this calculation, as discussedabove. It is the selected shift in the stopping position in servoencoder counts for varying the copy margins, assuming any said shift isselected. If no shift is selected this component becomes zero and dropsout of the formula.

Note that DIST can be preset to accommodate the actual position of thesensor 32 at whatever distance upstream of the registration position itis desired to position this sensor. Likewise, DIST can be changed toaccommodate different size platens or different desired registrationpositions on the photoreceptor or to accommodate different copy sheetregistration systems. A technical representative may electronicallyadjust the copier document registration to fit the particular mechanicaltolerances or variations of that particular copier simply by changingthis DIST count in the non-volatile memory of the copier. This is anadvantage over conventional copiers which require mechanical adjustmentsin one or more of the mechanical elements affecting mechanicalregistration, and may require special alignment tools or the like.Manufacturing may also be simplified in this manner. The electronicchange in the stored encoder counts can be tested immediately on testcopies of a marked test document to confirm proper registration.

Additional calculations or controls and/or imposed limitations on theoperation of the above described calculated registration system may beprovided. In particular, the registration calculation may furtherdesirably include insuring that the document is stopped for copying in aposition where it is fully overlying the platen and not extendingtherefrom, irrespective of the magnitude of the PS or MAG or SHIFTsignals, by presetting maximum and/or minimum REG counts for theparticular copier.

Specifically, the system may be programmed to indicate whenever the leadedge of the document has stopped, or will be stopped, beyond thedownstream edge of the platen, and therefore cannot be fully imaged.This could be provided by actuation of the downstream sensor 33 by thedocument lead edge prior to or during copying. However, this feature ispreferably, and more accurately, provided by having in a non-volatilememory the encoder count corresponding to the total available distancebetween sensor 32 and the downstream edge of the platen (or the distancefrom the preselected registration point 90 or DIST count to thedownstream edge of the platen). When the above-described formulaprovides a REG count which exceeds that downstream platen edge count, asignal may be flashed on the operator console by the controller 16and/or copying may be inhibited. Alternatively and preferably in thissituation the document may be stopped at the servo encoder countcorresponding to the document lead edge being at the downstream edge ofthe platen even though REG exceeds that count, i.e. providing analternative (maximum travel) stopping position. Alternatively oradditionally the optical ratio or paper size may be automaticallychanged.

There is a further, additional (and in some cases inter-related) featurewhich may be provided. This is to provide an operator indication orcontrol in the opposite situation, i.e. when the calculated REG count isso small that the platen transport 22 will not have driven that documenta sufficient distance for the trail edge of that document to have beenfed all the way onto the platen when the document feeder 22 is stoppedin the normally calculated REG count stopping position. This failure ofthe trail edge of the document to be on the platen at the calculatedstopping position for the lead edge thereof may be provided by sensingthe continued presence of a trail edge area of the document at thesensor 32 before or during copying. However, preferably this informationis provided by comparing the calculated REG to a preset minimumallowable REG count which is the encoder count of the document pathdistance from sensor 32 to the platen. The calculation of a REG which isless than this minimum in the above formula indicates to the controller16 that the trail edge would not be driven by the distance from thesensor 32 to the platen. As with the previously described downstreamproblem, this may be signaled to the operator to tell the operator tomake another selection in paper size or magnification ratio which willeliminate this problem. Alternatively, that may be done automatically,as by automatically changing the selected paper tray and/orautomatically changing the selected magnification ratio for thatdocument until an acceptable recalculated REG count is reached. That is,to require REG to exceed a preset minimum count in all cases to assurethat the trail edge of the document will always reach the platen beforecopying. If this change, or an oversize document, would also or thencause the lead edge of that same document to have a calculated REGstopping position beyond the downstream edge of the platen, then theadditional feature described above for that other problem mayautomatically come into play also. The controller can be programmed toprevent copying them or to make a choice as to which end of the documentwill not be on the platen.

A further optional feature which may be compatibly provided is toadditionally measure or calculate the actual dimensions of the documentbeing copied in its feeding direction and to utilize that information aswell. Document length (transverse dimension) may be calculated withsensors 31 as described above. This may also be provided by for theother dimension of the document for example detecting the lead edge ofthe document at sensor 32 and counting the servo encoder pulses requiredto transport that document from then until the sensing of the trail edgeof that document at sensor 32. (There may be some error due to velocityvariations until the document is under full control of the platentransport belt.) This document dimension in servo 24 encoder counts maybe compared to the calculated REG. It may be used, for example, toanticipate that that document width, for that particular selected copysize and magnification ratio, would cause that document's lead edge tobe stopped downstream of the downstream platen edge, and even to avoidthis automatically by automatically changing the magnification ratioand/or copy sheet size.

Turning now further to the functionally integral and partiallystructurally integral dual mode inverter/output system disclosed herein,a highly compact, reduced size, yet reliably feeding system is provided.Referring particularly to FIGS. 1 and 2, as previously noted only theinitial portion 61 of the inverter document reversing chute and itsbaffling are physically integral the pivotal RDH unit itself. Alsointegral and pivotable with the RDH unit are the reversible roller pairset 62 integral said partial chute 61 and its reversible drive. In theirreversible operating mode the rollers 62 provide an integral part of theinverter for inverting duplex documents being recirculated. In theirnon-reversing mode, initiated automatically by SADH input, the rollers62 rotate only in the direction to eject documents from partial chute 61out of its open end.

As shown in FIG. 1, the open output end of partial chute 61 communicatesdirectly with a stationary main inverter chute 80 whenever the RDH unit20 is in its normally closed operating position over the platen 12. Thatis, the outer ends of the partial baffles defining the partial chute 61open closely and directly into the entrance of larger and wider-spacedbaffling forming a main inverter (and output) chute 80. But this maininverter chute 80 is unconventionally not on the RDH unit 20. It isintegral the copier 10 instead, and therefore does not add to the sizeor mass of the RDH unit. Yet it provides a very desirable planar andhorizontal full-size inverter chute capable of handling a full range ofdocument sizes up to the largest size the RDH unit can recirculate. Thismain chute 80 is parallel the upper surface of the copier, and canprovide an extension of the work area on top of the copier. The mainchute 80 does not restrict or resist free movement of the document inits reversal. However the chute 80 confines the downstream half of thedocument which briefly rapidly extends from the partial chute 61, asillustrated in FIG. 1. This protects both the operator and the documentduring its rapid extension and reversal. The chute 80 also providesfurther guidance for a document being ejected rather than reversed. Thechute 80 is itself also open-ended for document output (see also FIG.2), and it's baffling or internal configuration is such as to assist inguiding a document being fed out from the open end of chute 80 into asuitable stacking area or tray, e.g. adjacent output restacking tray 84here. For example the lower baffle 86 of chute 80 may be a pivotableramp, pivotable from a horizontal position for document inverting intothe illustrated ramp position of FIG. 1 for assisting document ejectionand restacking. The upper baffle 85 is preferably a fixed housing or"doghouse" as shown, but may be removable for assisting in document jamclearances and may be translucent for document visability. It may haveinternal guide ribs as shown.

For even further compactness, the chute 80 and associated documentoutput area, here output restacking tray 84, may be integral a copieroutput module 82. This may be a portion or attachment to the uppersurface of a copier sorter or finishing module or other copy sheetreceiving means mounted at one end of the copier, as shown, or a trayunit attachment hung or otherwise fastened to the end of the copier. Ineither case, none of the upper surface workspace is occupied by eitherthe document inverter chute or document output, which is all in theintegral copier attachment. The module 82 itself, or as part of a copieroutput module, may be seperately shipped or installed rather thanincreasing the size of the main body or processor of the copier, and thedocument output and inverter path structure can itself be compact andremovable if desired. Utilizing the upper surface area of a copy sheetstapler or sticher unit module for the inverter chute 80 and outputrestacking tray 84 or the like is particularly desirable as this is anormally unused area and using it does not increase or substantiallyincrease the overall dimensions and floorspace of the combinedcopier/finisher unit. Note that no drives, sensors or moving parts arerequired in that (stationary) portion of the document inverter/outputunit here which is integral the copier rather than the RDH unit. All ofthese active components are desirably integral the RDH unit, yet most ofthe space normally required for an inversion path is not.

The use of the document ejection mode and path is not restricted to SADHinputted documents. It may also be used for example to eject a documentpreviously left on the platen in a prior copying operation, or to ejectdocuments for jam correction job recovery, if desired.

While the embodiments disclosed herein are preferred, it will beappreciated that they are merely examples, and that variousalternatives, modifications, variations or improvements may be made bythose skilled in the art from this teaching, which are intended to beencompassed by the following or subsequent claims:

What is claimed is:
 1. In a copier with a recirculating document handlerpivotally mounted to be operatively closable over an imaging station onthe upper surface of the copier, and a document inverter, and thecapability of automatically copying both sides of documents at saidimaging station by utilizing the document inverter to invert documentsbeing recirculated by the document handler, the improvement wherein:saiddocument inverter is only partially in said document handler andoperatively, but non-integrally, incorporates a generally planar andstationary document chute, said document chute being integrally mountedto said copier and not a physical part of, or pivotal with, saiddocument handler, to provide a more compact document handler yetautomatic document inversion capability, said document chute comprisingupper and lower baffles for containing and guiding a document forreversal therein by said document inverter and thereby providing anoperative portion of said document inverter, in said operatively closedposition of said document handler, said upper and lower baffles beinglaterally adjacent to said imaging station, and only operativelyconnecting with the other portions of said document inverter in saiddocument handler when said document handler is operatively closed oversaid imaging station.
 2. The copier of claim 1 wherein said documentchute has an open end remote from said imaging station, and saiddocument inverter is selectively alternatively operable to provide adocument output ejection path through said document chute and out ofsaid open end rather than document reversing therein.
 3. The copier ofclaim 1 wherein said at least a major portion of said upper and lowerbaffles defining said document chute are integral to copy sheet outputreceiving means integrally mounted to one side of said copier.
 4. Thecopier of claim 2 wherein said at least major portion of said upper andlower baffles defining said document chute are integral to copy sheetoutput receiving means integrally mounted to one side of said copier,and said copy sheet output receiving means also has an integral documentcatch tray communicating with said document chute.
 5. The copier ofclaim 3 wherein said document chute has an open end in said copy sheetoutput receiving means, and said document inverter is adapted toalternatively provide a document output ejection path through saiddocument chute and out of said open end, and wherein said copy sheetoutput receiving means further includes a document receiving trayoperably connecting with said open end to collect documents ejectedtherefrom.
 6. The copier of claim 1 wherein said at least a majorportion of said upper and lower baffles defining said document chute areintegral document collection tray means integrally mounted to saidcopier, and wherein said document chute opens into said documentcollection tray means, and wherein said document inverter is adapted toalternatively provide a document output ejection path through saiddocument chute and into said document collection tray means, which isadapted to collect documents so ejected.
 7. The copier of claim 1wherein said document chute is generally parallel to and contiguous withsaid upper surface of said copier.
 8. The copier of claim 3 wherein saiddocument chute is generally parallel to and contiguous with said uppersurface of said copier.
 9. The copier of claim 5 wherein said documentchute is generally parallel to and contiguous with said upper surface ofsaid copier.
 10. The copier of claim 1 wherein said document inverterincludes a selectably reversible document feeding means integral saiddocument handler and in direct document feeding communication with saiddocument chute when said document handler is closed over said imagingstation to provide reversible document feeding to and out of documentchute for said document inverting; and wherein said document inverterfurther includes upper and lower minor baffle portions smaller than thedimensions of documents to be reversed therein which baffle portions areautomatically aligned with said upper and lower baffles integral saidcopier when said document handler is closed over said imaging station.11. The copier of claim 10 wherein said reversible document feedingmeans is integral said upper and lower minor baffle portions.
 12. Thecopier of claim 10 wherein said document chute is generally parallel toand contiguous with said upper surface of said copier,and wherein saidmajor portions of said upper and lower baffles defining said documentchute are in document feeding communication with document collectionmeans integrally mounted to said copier, and wherein said document chuteopens into said document collection means, and wherein said selectivelyreversible document inverter is adapted to alternatively provide adocument output ejection path through said document chute and into saiddocument collection tray means, which is adapted to collect documents soejected.